This invention relates to an image processing system in which an image processing apparatus such as a printer is shared through a network.
In a conventional image processing system known as a so-called network printer, an image processing apparatus such as a printer is connected to a network such as a local area network (LAN) to be shared by terminal units including work stations (WSs), personal computers (PCs) and the like which are connected to this network.
In such an image processing system, when text data or graphic data (these two types of data are hereinafter generally referred to as image data) created in a terminal unit are to be output as a hard copy from a printer, the user of the terminal unit must know the functions of the printer before setting an operation mode for the printer. For example, the user must know which size of paper is available in the printer, whether the printer is capable of double-face printing, whether it has a sorter, and whether it is capable of automatic stapling. The user sets the operation mode on the basis of these functions of the printer.
Therefore, conventionally, a method has been adopted in which, for example as shown in Japanese Patent Unexamined Publication No. Hei. 2-178678, instructions defining an operation mode are output as a hard copy, and then the hard copy is fed into and read by the printer so that the operation mode is set. In another conventionally adopted method, a so-called printing protocol is installed on each terminal unit, and, when using a printer, this protocol is used to communicate with the printer to inquire about the functions thereof or the like.
In the method shown in Japanese Patent Unexamined Publication No. Hei. 2-178678, however, it is extremely troublesome to output the instructions for the operation mode as a hard copy.
In the method in which communication is performed using the printing protocol, since direct communication with a printer is necessary in each printing operation, there arise problems that the communication protocol is complicated and also that the printing protocol to be installed on terminal units is extremely large. These problems are noticeable particularly in recent years. Recently, a plurality of printers are often connected to a network, and accordingly these printers are provided with different printing protocols in order to allow terminal units to communicate with them. In this case, each terminal unit is required to install the printing protocols of all the printers connected to the network, or to install a conversion protocol for converting one printing protocol into another. When many printers are connected to the network, therefore, a very large volume of software or hardware is necessary for installing printing protocols or conversion protocols. Furthermore, when the network is to have a new printer having a printing protocol different from those of the existing printers, all the terminal units are required to install a new printing protocol or a conversion protocol for the new printer. This requires extremely troublesome efforts.
After a terminal unit requests a printer to start printing, the user of the terminal unit may sometimes wish to check the status of the printer, e.g., whether printing is properly completed, whether paper has been used up, or whether the printer is incapable of printing due to the malfunction thereof.
In order to meet such a user's demand, some methods have been proposed. In a known method, a printing protocol is used in the same manner as described above to directly communicate with the printer to obtain necessary information. In another known method, as disclosed in Japanese Patent Unexamined Publication No. Hei. 1-291566, units for switching lines coupled to copying machines are respectively connected to terminal units to collect information on the operation status of the copying machines, and collected information is sent to the terminal unit connected to the respective switching units. In other known methods such as disclosed in Japanese Patent Unexamined Publication Nos. Hei. 2-259662, Hei. 2-259663, Hei. 2-259664, Hei. 2-259665, Hei. 2-259666, Hei. 2-257153, Hei. 2-257154, Hei. 2-257155 and Hei. 2-257156, an information collecting unit connected to copying machines through a line collects information on errors or the like from the copying machines.
In the above-described prior art, however, a terminal unit is required to communicate with an image processing apparatus such as a printer in order to collect information on the functions or operation status of the image processing apparatus, information on the status of requested image processing operation, or the like. This leads to the same problems as those described above.